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A choropleth map (from Ancient Greek χῶρος (khôros) 'area, region', and πλῆθος (plêthos) 'multitude') is a type of statistical thematic map that uses pseudocolor, meaning color corresponding with an aggregate summary of a geographic characteristic within spatial enumeration units, such as population density or per-capita income.
Biogeography is a synthetic science, related to geography, biology, soil science, geology, climatology, ecology and evolution. Some fundamental concepts in biogeography include: allopatric speciation – the splitting of a species by evolution of geographically isolated populations; evolution – change in genetic composition of a population
Population pyramid. A population pyramid (age structure diagram) or " age-sex pyramid " is a graphical illustration of the distribution of a population (typically that of a country or region of the world) by age groups and sex; it typically takes the shape of a pyramid when the population is growing. [1] Males are usually shown on the left and ...
Due to population density, dispersal may relieve pressure for resources in an ecosystem, and competition for these resources may be a selection factor for dispersal mechanisms. Dispersal of organisms is a critical process for understanding both geographic isolation in evolution through gene flow and the broad patterns of current geographic ...
Antarctica is the fifth-largest continent, being about 40% larger than Europe, and has an area of 14,200,000 km 2 (5,500,000 sq mi). Most of Antarctica is covered by the Antarctic ice sheet, with an average thickness of 1.9 km (1.2 mi).
Occupancy–abundance relationship. In ecology, the occupancy–abundance ( O–A) relationship is the relationship between the abundance of species and the size of their ranges within a region. This relationship is perhaps one of the most well-documented relationships in macroecology, and applies both intra- and interspecifically (within and ...
Cline (biology) In biology, a cline is a measurable gradient in a single characteristic (or biological trait) of a species across its geographical range. [1] Clines usually have a genetic (e.g. allele frequency, blood type ), or phenotypic (e.g. body size, skin pigmentation) character. They can show either smooth, continuous gradation in a ...
Desert. A desert is a landscape where little precipitation occurs and, consequently, living conditions create unique biomes and ecosystems. The lack of vegetation exposes the unprotected surface of the ground to denudation. About one-third of the land surface of the Earth is arid or semi-arid.